The present invention relates to a control system including two control columns that are coupled to enable controlled members to be placed in required positions.
The invention relates more particularly, although not exclusively, to the application of a control system of the above kind to positioning the control surfaces—in particular the pitch and roll control surfaces—of an aircraft having a cockpit with dual controls.
The document U.S. Pat. No. 5,291,113 discloses an aircraft control system of the above type comprising two control columns, each of which is mounted on a gimbal and has two degrees of freedom assigned to the respective controlled members to be moved, and, for each of said control columns, and assigned to said respective degrees of freedom:
a) two actuators for applying to their associated control column either a resisting torque or a displacement torque for the associated degree of freedom,
b) two control circuits each of which is adapted:
on the one hand, to control the actuator for the associated degree of freedom so that it supplies a resisting torque opposing each manipulation of a first of the control columns exerted for that degree of freedom, and
on the other hand, to bring about, as a function of said manipulation of the first control column, a displacement of the second control column of the same amplitude, in the same direction and for the same degree of freedom,
c) two control column position detectors for supplying to the respective control circuits an associated control column position input signal,
said control system further comprising:
d) means for controlling displacement of said controlled members as a function of signals supplied by said sensors.
In the above prior art control system, each control circuit is entirely electronic, the control columns being loaded by electric motors that alone provide the displacement torques and the resisting torques exerted on the control columns.
Consequently, in the event of a failure in the control system, in particular an electrical failure, not only is the coordination of the movement of the two control columns compromised but also the resisting forces can no longer be applied to the control columns, which seriously compromises safety, and is unacceptable in many situations and in particular in the field of avionics.
An object of the invention is to propose a control system of the indicated type that does not have these drawbacks.